The present invention relates to a method and arrangement for supplying a waste heat boiler or exchanger with exhaust gas from a gas turbine, whereby the gas is guided through a diverter having a pivotable butterfly valve, and whereby when the valve is opened to initiate entry of exhaust gas into the waste heat exchanger, the gas flows about the free edge of the valve.
During start up of the waste heat exchanger, which is disposed downstream of a gas turbine and a diverter, due to different thermal loads localized critical material stresses occur in the components of the exchanger; these are caused by localized concentrations of higher temperature in the exhaust gas that is supplied. These concentrations are produced by partial opening of the diverter as exhaust gas flows over the free edge of the butterfly valve, possibly in conjunction with the gas turbine swirl imparted to the gas flow. Accordingly, when a diverter is used, which upon demand can convey the exhaust gas of the gas turbine to a bypass flue, the exchanger components become costly with regard to wall thickness, curved expansion sections, and control means.
It is therefore an object of the present invention to provide a method and arrangement of the aforementioned general type according to which the waste heat exchanger can have a far less expensive configuration.